DISTANT GALAXY FOUND TO BE LARGEST KNOWN

AP

Published: March 13, 1987

WASHINGTON, March 12—
Astronomers say they have discovered that a galaxy observed by astronomers for two decades is 13 times as big as the Milky Way and others of average size. This would make the galaxy, Markarian 348, the largest known.

The galaxy, 300 million light-years from Earth in the direction of the constellation Andromeda, had been thought to be about the size of the Milky Way.

Dr. Susan M. Simkin, professor of astronomy at Michigan State University, made the discovery with Dr. Hong-Jun Su of Nanjing, China, formerly a visiting scientist at Michigan State, and Dr. Jacqueline van Gorkom and Dr. John Hibbard of the National Radio Astronomy Observatory at Socorro, N.M.

Markarian 348 is an oddly shaped spiral of stars and gases that puts out tremendous amounts of energy, according to a report to be published Friday in the journal Science.

Researchers say the galaxy is 1.3 million light-years in diameter. The Milky Way, of which the Earth and its solar system are part, is about 100,000 light-years in diameter. A light-year is about six trillion miles.

Markarian 348 appears to have at least one and possibly two long spiraling arms tightly wound near the center and branching out at irregular angles.

As interesting as the size of the body, the scientists report, is the action of the great cloud of hydrogen that surrounds it. The cloud appears to be moving in a tidal fashion under the gravitational influence of a smaller nearby galaxy, the astronomers said. The gravity of the small galaxy appears to make the gas undulate around the core of Markarian 348, she said. The gas gains momentum from the orbital motion of the smaller galaxy, causing it to spread out.

Scientists have long speculated on the existence of tidal effects as the cause of spiraling movement in galaxies, but it has never before been observed in detail, she said.

The recent observations, using a large radio telescope in New Mexico to penetrate intervening light and gas, disclosed the hidden properties.